Final answer:
The question requires using the loan payment formula to find the highest APR loan rate for a $77,000 loan with monthly payments of $1,300 over 78 months with monthly compounding.
Step-by-step explanation:
The question involves calculating the highest APR loan rate for a sailboat purchase, which is a problem typically encountered in the mathematics of finance. To solve for the rate, you can use the loan payment formula, which is based on the present value of an annuity. This question is similar to determining the monthly loan payment for a mortgage but in reverse, since you're solving for the interest rate given the monthly payment, loan amount, and the number of payments.
Given that you want to borrow $77,000 and can afford monthly payments of $1,300, the loan's term is 78 months, and the compounding is monthly, you would set up the formula accordingly and use iteration or a financial calculator to find the highest interest rate you can afford.